Metal organic framework

ABSTRACT

A solid metal organic framework composition comprising a solid oxyanion-modified metal organic framework wherein the oxyanion loading is at least 2 per node.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a non-provisional application which claims thebenefit of and priority to U.S. Provisional Application Ser. No.63/091,060 filed Oct. 13, 2020, entitled “Methods of Selection, Forming,and Using Metal Organic Frameworks,” which is hereby incorporated byreference in its entirety.

STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

None.

FIELD OF THE INVENTION

A metal organic framework.

BACKGROUND OF THE INVENTION

Acid catalysts are critical for industrial hydrocarbon transformations.Reactions such as cracking, alkylation, isomerization, oligomerizationand hydration/dehydration, which are important steps in the productionof chemicals and fuels, are acid catalyzed. The acid strengthrequirement for the catalysts differ for these processes.

Solid acids are deemed easier to handle and more environmentally benignthan liquid acids. Some important families of solid acid catalystsinclude zeolites, oxides, clays, and polymer resins. These catalystfamilies are under continuous development to achieve new reactivitiesand improve catalytic performance.

Metal-organic frameworks (MOFs) are emerging as a promising class ofheterogeneous catalysts due to their unique physical and chemicalproperties including high surface area, adjustable pore structure,tunable element composition, and the potential for surface modification.MOFs are porous, crystalline materials made of alternating organic(linkers) and inorganic building units (nodes). Importantly, theirwell-defined molecular structure and chemical environment enable thecatalytic conversion of complex feedstocks into products with highselectivity and high conversion. The interest in MOFs in the field ofcatalysis has been attributed to the ability of these materials tobridge the gap between homogenous and heterogenous catalysis. This isdue to the ability of MOFs to recreate chemically precise catalyticactive sites such as those found in homogenous catalysis in aheterogenous support. In recent years, acidic MOFs have attractedsignificant research interest because of their potential application ina large class of acid-catalyzed reactions, including isomerization,cyclization, biomass transformation, benzylation, and aromaticalkylation.

An important refinery process that requires high acid strength catalystsis olefin-paraffin alkylation. The alkylation process produceshigh-octane gasoline blend called alkylate by reacting light olefins(C₂-C₄) with isoparaffins (C₄-C₅). Most commonly, isobutane is reactedwith olefins (butenes) derived from refinery fluid catalytic crackingunits to produce a product that consists of C₆-C₉ branched paraffins.Out of all the desired products, trimethylpentanes (TMPs) are typicallythe primary component. TMPs have research octane numbers (RONs) of100-109.6. Other lower-octane reaction products such as dimethylhexanes(DMHs) and dimethylpentanes are also present.

For alkylation, the current catalyst systems used in refineries areliquid hydrofluoric acid (HF) and sulfuric acid (H₂SO₄). These strongacids are required to promote the hydride transfer reaction between anisoparaffin and hydrocarbon carbocation. Alternative alkylationcatalysts are of interest because of risks associated with traditionalHF- and H₂SO₄-based alkylation. Catalysts such as zeolites, ionicliquids (ILs), heteropolyacids (HPAs), acidic resins, and sulfatedtransition metal oxides (TMOs) have been shown to catalyze alkylation,but technical challenges—including low activity and rapiddeactivation—exist.

Similarly, to alkylation, oligomerization is a hydrocarbon upgradingprocess that is an attractive, low-cost means to lower the vaporpressure of light naphtha streams that may be orphaned by futureregulatory standards. This process can take olefins in the gas phase(C₂-C₄) and convert them to heavier liquid hydrocarbons suitable to alarge array of applications such as: naphtha (C₆-C₉), diesel (C₉-C₁₂),jet fuel (C₁₂-C₁₆) and specialty chemicals. In order to undergooligomerization, a source of acidity is also required much like inalkylation chemistry. This is due because both reactions sharing acommon intermediate which is a carbocation formed when an olefin isprotonated and stabilized in the surface of the catalyst. Inoligomerization, there is no requirement for hydride transfer in thereaction mechanism allowing the process to occur with lower acidityrequirements as compared to alkylation. Nevertheless, an importantcorrelation exists wherein the smaller the olefin, the higher theacidity required to oligomerize the feed. Thus, high acidity materialshave a larger operating window since they can utilize a wider range offeeds.

Materials for oligomerization can be found in the literature and oftenoverlap with materials used for alkylation due to the shared chemicalintermediates between both processes. These materials include:Aluminosilicates, zeolites, ionic liquids (ILs), heteropolyacids (HPAs),acidic resins, and sulfated transition metal oxides (TMOs). Despite thebroad range of materials, a diverse set of challenges exist. In manycases fast deactivation is observed due to formation of large oligomersthat block the channels of materials and high conversion often isaccompanied by poor selectivity to the desired products.

BRIEF SUMMARY OF THE DISCLOSURE

A solid metal organic framework composition comprising a solidoxyanion-modified metal organic framework wherein the oxyanion loadingis at least 2 per node.

BRIEF DESCRIPTION OF THE DRAWINGS

A more complete understanding of the present invention and benefitsthereof may be acquired by referring to the follow description taken inconjunction with the accompanying drawings in which:

FIG. 1 depicts linkers currently used to build MOFs.

FIG. 2 depicts results from analysis of MOFs.

FIG. 3 depicts results from analysis of MOFs.

FIG. 4 depicts results from analysis of MOFs.

FIG. 5a depicts conversion v. catalyst age alkylation results.

FIG. 5b depicts selectivity v. conversion results.

FIG. 6a depicts conversion v. catalyst age alkylation results.

FIG. 6b depicts selectivity v. conversion results.

FIG. 7a depicts conversion v. catalyst age alkylation results.

FIG. 7b depicts selectivity v. conversion results.

FIG. 8a depicts supercritical alkylation results.

FIG. 8b depicts supercritical alkylation results.

FIG. 9 depicts activation results.

FIG. 10 depicts selectivity results.

FIG. 11 depicts a reaction scheme.

FIG. 12 depicts example MOF building units.

FIG. 13 depicts example MOF ligands.

FIG. 14 depicts non-limiting representative sultones.

FIG. 15 depicts alkylation results.

FIG. 16 depicts alkylation results.

FIG. 17 depicts alkylation results.

FIG. 18 depicts supercritical alkylation results.

FIG. 19 depicts the alkylation results.

FIG. 20 depicts the alkylation results.

FIG. 21 depicts the alkylation results.

FIG. 22 depicts the oligomerization results.

FIG. 23 depicts the product selection results.

FIG. 24 depicts the conversion results.

FIG. 25 depicts long term stability results.

FIG. 26 depicts a non-limiting embodiment of the process.

FIG. 27 depicts oligomerization results.

DETAILED DESCRIPTION

Turning now to the detailed description of the preferred arrangement orarrangements of the present invention, it should be understood that theinventive features and concepts may be manifested in other arrangementsand that the scope of the invention is not limited to the embodimentsdescribed or illustrated. The scope of the invention is intended only tobe limited by the scope of the claims that follow.

A process comprising a heterogeneous reaction between a hydrocarbon feedon a solid metal-organic framework-supported or based catalyst to form amodified hydrocarbon stream comprising essentially of C₆₊ hydrocarbons.Non-limiting examples of MOFs-supported catalytically active componentsthat can be used include heteropolyacids, sulfonic acids, oxyanions suchas oxyanions-modified metal oxides, and ionic-type functionalities.

This arrangement details the preparation of different types of acidicMOF-based catalysts and their applications. The MOF-based catalysts canconsist of two components: the MOF support and the acid sites that arebound to the MOF support. The acid sites can dictate the acid strengthand therefore the type of reaction that can be catalyzed by the MOFbased catalysts. Different acid sites require different binding motifson the MOF support. The acid site can be encapsulated in the pore spaceof the MOF, or it could be bound to the MOF by attachment to the MOFnode, linker or any non-linker ligand present in the MOF structure. Theacid sites can be incorporated in the MOF support during the synthesisof the MOF, or they can be introduced to the MOF post-synthesis. The MOFsupport can influence mass diffusion, acid site dispersion andenvironment related to catalytic activity.

In a non-limiting example, the MOF support features a suitable pore andaperture size to encapsulate the acid species.

In a non-limiting example, the MOF support features nucleophilic groupssuch as hydroxyl, amino, thiol, and phosphine, among others. Thesegroups can serve as attachment points for the acid species.

In a non-limiting example, the MOF support features a suitable metaloxide-based node that interacts with an anionic species to form an acidsite.

In other non-limiting examples, the catalytically active components canbe added to the solid metal organic frameworks via solutionimpregnation, one-pot synthesis, encapsulation, adsorption, deposition,grafting and/or covalent attachment reactions.

In one embodiment the loading of the catalytic active components on thesolid metal organic framework can be greater than 5% by weight, or inother embodiments even 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%,60%, 65%, even 70% or more by weight.

In addition, this arrangement describes the composition of a new familyof acidic MOFs bearing halogenated and/or non-halogenated sulfonic acidfunctionalities as acid sites for use as alternative solid acidcatalysts for different organic transformations. The reactivity of thisfamily of MOFs can be tuned by changing the type of MOF and sulfonicacid functionality to meet catalytic application demands. In oneexample, the sulfonic acid functionalized MOF has enough strength tocatalyze the olefin-paraffin alkylation reaction.

The heterogeneous reaction can be either an olefin-paraffin alkylationreaction or an olefin oligomerization reaction. As an example, for somealkylation reactions, the hydrocarbon component produced is a C₆₊paraffinic hydrocarbon. As another example, for some oligomerizationreactions, the hydrocarbon component produced is a C₆₊ olefinichydrocarbon or even an C₈₊ olefinic hydrocarbon.

In one embodiment, the hydrocarbon feed comprises and/or comprisesessentially of C₂ to C₅ hydrocarbons such as light hydrocarbons. Theselight hydrocarbons feed can be olefins such as propylene, butyleneand/or isoparaffins such as isobutane. In another embodiment, theheterogenous reaction between a solid metal organic framework and ahydrocarbon feed which can be a gaseous hydrocarbon feed, a liquidhydrocarbon feed, or a supercritical hydrocarbon feed.

In this arrangement, we describe a process that uses an acidic MOF thatcan convert a hydrocarbon feed of light olefins (C₃-C₆) and isoparaffins(C₄-C₅) to heavier, more valuable products, such as alkylate which is ablend stock for high octane gasoline. This product effluent isforecasted to have great growth potential despite the forecasted changesin gasoline demand. In the refining process many of these hydrocarbonfeeds or light olefins (especially C4s) end up as feedstock forprocesses such as alkylation which can produce valuable alkylate, suchas high octane gasoline components.

In this arrangement we describe a new process that uses an acidic MOFthat can selectively oligomerize a hydrocarbon feed of light olefins(C₃-C₆) to heavier more valuable products such as the modifiedhydrocarbon stream which can be high octane gasoline, low sulfur diesel,jet fuel, specialty solvents or synthetic lube oils, which have beenforecast to have great growth potential despite the forecasted changesin gasoline demand.

In another embodiment, the proposed arrangement utilizes the highselectivity of the MOF material and engineered conditions to integrateoligomerization and alkylation to maximize the value of the productstream. In this integrated process, the low value olefins areselectively oligomerized while the high value olefins are alkylated toform high octane gasoline components.

In a non-limiting embodiment, the process is able to achieve a modifiedhydrocarbon stream with a conversion rate of C₆+ hydrocarbons at a rategreater than 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, even greater than60%.

In a non-limiting embodiment, the process is able to achieve a modifiedhydrocarbon stream with a selectivity rate of C₆+ hydrocarbons at a rategreater than 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, even greater than60%.

Other potential applications for acid MOFs include olefinoligomerization, C₂-C₄ olefins/i-C₄ and iC₅ isoparaffin alkylation,olefin isomerization, and olefin/aromatic alkylation.

MOF Supports

MOFs are built up of metal cation containing nodes bridged by organiclinkers. Non limiting examples of linkers and nodes that can be used aregenerally described below.

MOF Linkers and Non-Linker ligands

The organic linkers of the MOFs of the arrangement may be any linkermolecule or molecule combination capable of binding to at least twoinorganic nodes and comprising an organic moiety. Thus, the linker maybe any of the linkers conventionally used in MOF production. These aregenerally compounds with at least two node-binding groups, e.g.carboxylates, optionally with extra functional groups which do not bindthe nodes but may bind metal ions on other materials it is desired toload into the MOF. The linkers moreover typically have rigidifyinggroups between the node-binding groups to facilitate 3D MOF formation.Examples of suitable organic linker compounds include oxalic acid,ethyloxalic acid, fumaric acid, 1,3,5-benzene tricarboxylic acid (BTC),1,3,6,8-tetrakis(p-benzoic acid)pyrene (TBAPy), 1,3,5-benzene tribenzoicacid (BTB), DCPB, benzene tribiphenylcarboxylic acid (BBC),5,15-bis(4-carboxyphenyl) zinc (II) porphyrin (BCPP), 1,4-benzenedicarboxylic acid (BDC), 2-amino-1,4-benzene dicarboxylic acid (R3-BDCor H2N BDC), 1,1′-azo-diphenyl 4,4′-dicarboxylic acid,cyclobutyl-1,4-benzene dicarboxylic acid (R6-BDC), benzene tricarboxylicacid, 2,6-naphthalene dicarboxylic acid (NDC), 1,1′-biphenyl4,4′-dicarboxylic acid (BPDC), 2,2′-bipyridyl-5,5′-dicarboxylic acid,adamantane tetracarboxylic acid (ATC), adamantane dibenzoic acid (ADB),adamantane teracarboxylic acid (ATC), dihydroxyterephthalic acid(DHBDC), biphenyltetracarboxylic acid (BPTC), tetrahydropyrene2,7-dicarboxylic acid (HPDC), dihydroxyterephthalic acid (DHBC), pyrene2,7-dicarboxylic acid (PDC), pyrazine dicarboxylic acid, acetylenedicarboxylic acid (ADC), camphor dicarboxylic acid, fumaric acid,benzene tetracarboxylic acid, 1,4-bis(4-carboxyphenyl)butadiyne,nicotinic acid, and terphenyl dicarboxylic acid (TPDC). Other acidsbesides carboxylic acids, e.g. boronic acids may also be used. A mixtureof linkers may be used to introduce functional groups within the porespace, e.g. by using aminobenzoic acid to provide free amine groups orby using a shorter linker such as oxalic acid.

In one embodiment, the linker comprises an organic-based parent chaincomprising alkyl, hetero-alkyl, alkenyl, hetero-alkenyl, alkynyl,hetero-alkynyl, one or more cycloalkyl rings, one or more cycloalkenylrings, one or more cycloalkynyl rings, one of more aryl rings, one ormore heterocycle rings, or any combination of the preceding groups,including larger ring structures composed of linked and/or fused ringsystems of different types of rings; wherein this organic-based parentchain may be further substituted with one or more functional groups,including additional substituted or unsubstituted hydrocarbons andheterocycle groups, or a combination thereof; and wherein the linkercontains at least one (e.g. 1, 2, 3, 4, 5, 6, . . . ) linking cluster.

In a yet further embodiment, the linker of the metal organic frameworkhas an organic-based parent chain that is comprised of one or moresubstituted or unsubstituted rings; wherein one or more of these ringsare further substituted with one or more functional groups, includingadditional substituted or unsubstituted hydrocarbons and heterocyclegroups, or a combination thereof, and wherein the linker contains atleast one (e.g., 1, 2, 3, 4, 5, 6, or more) linking cluster that iseither a carboxylic acid, amine, thiol, cyano, nitro, hydroxyl, orheterocycle ring heteroatom, such as the N in pyridine.

In another embodiment, the linker of the metal organic framework has anorganic-based parent chain that is comprised of one or more substitutedor unsubstituted rings; wherein one or more of these rings are furthersubstituted with one or more functional groups, including additionalsubstituted or unsubstituted hydrocarbons and heterocycle groups, or acombination thereof; and wherein the linker contains at least one (e.g.,1, 2, 3, 4, 5, 6, or more) carboxylic acid linking cluster.

The non-linker ligands of the MOFs of the arrangement may be any ligandmolecule or molecule combination capable of binding to one inorganicnode and comprising an organic moiety. These are generally compoundswith one node-binding group, e.g. carboxylates, with or without extrafunctional groups that do not bind the nodes but may react with and/orbind other species such as electrophiles and acid site precursors thatare desired to be used to functionalize the MOF.

In a certain embodiment the pore aperture of the MOF support iscontrolled by the length of the linker.

MOF Nodes

The inorganic nodes of MOFs can be synthesized using metal ions havingdistinctly different coordination geometries, in combination with aligand possessing multidentate functional groups, and a suitabletemplating agent. In general, the inorganic nodes could be one or moremetal-based nodes from Group 1 through 16 metals of the IUPAC PeriodicTable of the Elements including actinides, and lanthanides, andcombinations thereof. Examples of metal ions in the node can include:Mg²⁺, Ca²⁺, Sr²⁺, Ba²⁺, Sc³⁺, Y³⁺, Ti⁴⁺, Zr⁴⁺, Ce⁴⁺, Hf⁴⁺, V⁴⁺, V³⁺,V²⁺, Nb³⁺, Ta³⁺, Cr³⁺, Mo³⁺, W³⁺, Mn³⁺, Mn²⁺, Re³⁺, Re²⁺, Fe³⁺, Fe³⁺,Ru³⁺, Ru²⁺, Os³⁺, Os²⁺, Co³⁺, Co²⁺, Rh²⁺, Rh⁺, Ir²⁺, Ir⁺, Ni²⁺, Ni+,Pd²⁺, Pd⁺, Pt²⁺, Pt⁺, Cu²⁺, Cu⁺, Ag⁺, Au⁺, Zn²⁺, Cd²⁺, Hg²⁺, Al³⁺, Ga³⁺,In³⁺, Tl³⁺, Si⁴⁺, Si²⁺, Ge⁴⁺, Ge²⁺, Sn⁴⁺, Sn²⁺, Pb⁴⁺, Pb²⁺, As⁵⁺, As³⁺,As⁺, Sb⁵⁺, Sb³⁺, Sb⁺, and Bi⁵⁺, Bi³⁺, Bi⁺; along with the correspondingmetal salt counteranion. As used herein, the nodes refer to both metaland metalloid ions. Generally, the nodes that can be useful include:Sc³⁺, Zr⁴⁺, Ce⁴⁺, Hf⁺, Ti⁴⁺, V⁴⁺, V³⁺, V²⁺, Cr³⁺, Mo³⁺, Mn³⁺, Mn²⁺,Fe³⁺, Fe²⁺, Ru³⁺, Ru²⁺, Os³⁺, Os²⁺, Co³⁺, Co²⁺, Rh²⁺, Rh⁺, Ir²⁺, Ir⁺,Ni⁺, Pd²⁺, Pd⁺, Pt²⁺, Pt⁺, Cu²⁺, Cu⁺, Ag⁺, Au⁺, Zn²⁺, Cd²⁺, Al³⁺, Ga³⁺,In³⁺, Ge⁴⁺, Ge²⁺, Sn⁴⁺, Sn²⁺, Pb⁴⁺, Pb²⁺, Sb⁵⁺, Sb³⁺, Sb⁺, and Bi⁵,Bi³⁺, Bi⁺; along with the corresponding metal salt counteranion. Apreferred group of nodes includes: Sc³⁺, Zr⁴, Ce⁴⁺, Hf⁴, Ti⁴⁺, V⁴⁺, V³⁺,Cr³⁺, Mo³⁺, Mn³⁺, Mn²⁺, Fe³⁺, Fe²⁺, Co³⁺, Co²⁺, Ni²⁺, Ni⁺, Cu²⁺, Cu⁺,Ag⁺, Zn²⁺, Cd²⁺, Al³⁺, Sn⁴⁺, Sn²⁺, and Bi⁵⁺, Bi³⁺, Bi⁺; along with thecorresponding metal salt counteranion. More preferably the nodes usedare selected from the group consisting of: Zr⁴⁺, Ce⁴⁺, Hf⁴⁺, Cr³⁺, Mn³⁺,Mn²⁺, Fe³⁺, Fe²⁺, Co³⁺, Co²⁺, Ni²⁺, Ni⁺, Cu²⁺, Cu⁺, Ag⁺, Zn²⁺, Cd²⁺,Al³⁺ along with the corresponding metal salt counteranion. Mostpreferably the nodes useful in this arrangement are selected from thegroup consisting of: Zr⁴⁺, Ce⁴⁺, Hf⁴⁺, Cr³⁺, Fe³⁺, Fe²⁺, Co³⁺, Co²⁺,Ni²⁺, Ni⁺, Cu²⁺, Cu⁺, Zn²⁺, Al³⁺ along with the corresponding metal saltcounteranion. An especially preferred group of nodes that can be usedinclude: Zr⁴⁺, Ce⁴⁺, Hf⁴⁺, Cr³⁺, Fe³⁺, Co³⁺, Co²⁺, Ni²⁺, Ni⁺, Zn²⁺, Al³⁺along with the corresponding metal salt counteranion.

In yet another embodiment, one or more metals that can be used in the(1) synthesis of frameworks, (2) exchanged post synthesis of theframeworks, and/or (3) added to a framework by forming coordinationcomplexes with post framework reactant functional group(s) include, butare not limited to, Li⁺, Na⁺, K⁺, Rb⁺, Cs⁺, Be²⁺, Mg²⁺, Ca²⁺, Sr²⁺,Ba²⁺, Sc²⁺, Sc²⁺, Sc⁺, Y³⁺, Y²⁺, Y⁺, Ti⁺, Ti³⁺, Ti²⁺, Zr⁴⁺, Zr³⁺, Zr²⁺,Hf⁴⁺, Hf³⁺, V⁵⁺, V⁴⁺, V³⁺, V²⁺, Nb⁵⁺, Nb⁴⁺, Nb³⁺, Nb²⁺, Ta⁵⁺, Ta⁴⁺,Ta³⁺, Ta²⁺, Cr⁶⁺, Cr⁵⁺, Cr⁴⁺, Cr³⁺, Cr²⁺, Cr⁺, Cr, Mo⁶⁺, Mo⁵⁺, Mo⁴⁺,Mo³⁺, Mo²⁺, Mo+, Mo, W⁶⁺, W⁵⁺, W⁴⁺, W³⁺, W²⁺, W+, W, Mn⁷⁺, Mn⁶⁺, Mn⁵⁺,Mn⁴⁺, Mn³⁺, Mn²⁺, Mn⁺, Re⁷⁺, Re⁶⁺, Re⁵⁺, Re⁴⁺, Re³⁺, Re²⁺, Re+, Re,Fe⁶⁺, Fe⁴⁺, Fe³⁺, Fe²⁺, Fe⁺, Fe, Ru⁸⁺, Ru⁷⁺, Ru⁶⁺, Ru⁴⁺, Ru³⁺, Ru²⁺,Os⁸⁺, Os⁷⁺, Os⁶⁺, Os⁵⁺, Os⁴⁺, Os³⁺, Os²⁺, Os⁺, Os, Co⁵⁺, Co⁴⁺, Co³⁺,Co²⁺, Co⁺, Rh⁶⁺, Rh⁵⁺, Rh⁴⁺, Rh³⁺, Rh²⁺, Rh+, Ir⁶⁺, Ir⁵⁺, Ir⁴⁺, Ir³⁺,Ir²⁺, Ir+, Ir, Ni³⁺, Ni²⁺, Ni+, Ni, Pd⁶⁺, Pd⁴⁺, Pd²⁺, Pd+, Pd, Pt⁶⁺,Pt⁵⁺, Pt⁴⁺, Pt³⁺, Pt²⁺, Pt+, Cu⁴⁺, Cu³⁺, Cu²⁺, Cu⁺, Ag³⁺, Ag²⁺, Ag+,Au⁵⁺, Au⁴⁺, Au³⁺, Au²⁺, Au+, Zn²⁺, Zn⁺, Zn, Cd²⁺, Cd⁺, Hg⁴⁺, Hg²⁺, Hg⁺,B³⁺, B²⁺, B⁺, Al³⁺, Al²⁺, Al⁺, Ga³⁺, Ga²⁺, Ga⁺, In³⁺, In²⁺, In1⁺, Tl³⁺,Tl⁺, Si⁴⁺, Si³⁺, Si²⁺, Si⁺, Ge⁴⁺, Ge³⁺, Ge²⁺, Ge⁺, Ge, Sn⁴⁺, Sn²⁺, Pb⁴⁺,Pb²⁺, As⁵⁺, As³⁺, As²⁺, As⁺, Sb⁵⁺, Sb³⁺, Bi⁵⁺, Bi³⁺, Te⁶⁺, Te⁵⁺, Te⁴⁺,Te²⁺, La³⁺, La²⁺, Ce⁴⁺, Ce³⁺, Ce²⁺, Pr⁴⁺, Pr³⁺, Pr²⁺, Nd³⁺, Nd²⁺, Sm³⁺,Sm²⁺, Eu³⁺, Eu²⁺, Gd³⁺, Gd²⁺, Gd+, Tb⁴⁺, Tb³⁺, Tb²⁺, Tb⁺, Db³⁺, Db²⁺,Ho³⁺, Er³⁺, Tm⁴⁺, Tm³⁺, Tm²⁺, Yb³⁺, Yb²⁺, LU³⁺, and any combinationthereof, along with corresponding metal salt counter-anions.

Preparation of MOF Supports

The preparation of the MOFs in the disclosure can be carried out ineither an aqueous, non-aqueous solvents or in a solvent-free system. Thesolvent may be polar or non-polar, or a combination thereof, as the casemay be. The reaction mixture or suspension comprises a solvent system,linker or moieties, and a metal or a metal/salt complex. The reactionsolution, mixture or suspension may further contain a templating agent,growth modulator or other non-linker ligands, catalytically activecomponent or combinations thereof. The reaction mixture may be heated atan elevated temperature or maintained at ambient temperature, dependingon the reaction components.

Examples of non-aqueous solvents that can be used in the reaction tomake the MOF and/or used as non-aqueous solvent for a post synthesizedMOF reaction, include, but is not limited to: n-hydrocarbon basedsolvents, such as pentane, hexane, octadecane, and dodecane; branchedand cyclo-hydrocarbon based solvents, such as cycloheptane, cyclohexane,methyl cyclohexane, cyclohexene, cyclopentane; aryl and substituted arylbased solvents, such as benzene, toluene, xylene, chlorobenzene,nitrobenzene, cyanobenzene, naphthalene, and aniline; mixed hydrocarbonand aryl based solvents, such as, mixed hexanes, mixed pentanes, naptha,and petroleum ether; alcohol based solvents, such as, methanol, ethanol,n-propanol, isopropanol, propylene glycol, 1,3-propanediol, n-butanol,isobutanol, 2-methyl-1-butanol, tert-butanol, 1,4-butanediol,2-methyl-1-pentanol, and 2-pentanol; amide based solvents, such as,dimethylacetamide, dimethylformamide (DMF), diethylformamide (DEF),formamide, N-methylformamide, N-methylpyrrolidone, and 2-pyrrolidone;amine based solvents, such as, piperidine, pyrrolidine, collidine,pyridine, morpholine, quinoline, ethanolamine, ethylenediamine, anddiethylenetriamine; ester based solvents, such as, butylacetate,sec-butyl acetate, tert-butyl acetate, diethyl carbonate, ethyl acetate,ethyl acetoacetate, ethyl lactate, ethylene carbonate, hexyl acetate,isobutyl acetate, isopropyl acetate, methyl acetate, propyl acetate, andpropylene carbonate; ether based solvents, such as, di-tert-butyl ether,diethyl ether, diglyme, diisopropyl ether, 1,4-dioxane,2-methyltetrahydrofuran, tetrahydrofuran (THF), and tetrahydropyran;glycol ether based solvents, such as, 2-butoxyethanol, dimethoxyethane,2-ethoxyethanol, 2-(2-ethoxyethoxy)ethanol, and 2-methoxyethanol;halogenated based solvents, such as, carbon tetrachloride,chlorobenzene, chloroform, 1,1-dichloroethane, 1,2-dichloroethane,1,2-dichloroethene, dichloromethane (DCM), diiodomethane,epichlorohydrin, hexachlorobutadiene, hexafluoro-2-propanol,perfluorodecalin, perfluorohexane, tetrabromomethane,1,1,2,2-tetrachloroethane, tetrachloroethylene, 1,3,5-trichlorobenzene,1,1,1-trichloroethane, 1,1,2-trichloroethane, trichloroethylene,1,2,3-trichloropropane, trifluoroacetic acid, and2,2,2-trifluoroethanol; inorganic based solvents, such as hydrogenchloride, ammonia, carbon disulfide, thionyl chloride, and phosphoroustribromide; ketone based solvents, such as, acetone, butanone,ethylisopropyl ketone, isophorone, methyl isobutyl ketone, methylisopropyl ketone, and 3-pentanone; nitro and nitrile based solvents,such as, nitroethane, acetonitrile, and nitromethane; sulfur basedsolvents, dimethyl sulfoxide (DMSO), methylsulfonylmethane, sulfolane,isocyanomethane, thiophene, and thiodiglycol; urea, lactone andcarbonate based solvents, such as1-3-dimethyl-3,4,5,6-tetrahydro-2(1H)-pyrimidinone (DMPU),1-3-dimethyl-2-imidazolidinone, butyrolactone, cis-2,3-butylenecarbonate, trans-2,3-butylene carbonate, 2,3-butylene carbonate; greensolvents such as cyrene and valerolactone; ionic liquids; carboxylicacid based solvents, such as formic acid, acetic acid, chloracetic acid,trichloroacetic acid, trifluoroacetic acid, propanoic acid, butanoicacid, caproic acid, oxalic acid, and benzoic acid; boron and phosphorousbased solvents, such as triethyl borate, triethyl phosphate, trimethylborate, and trimethyl phosphate; deuterium containing solvents, such asdeuterated acetone, deuterated benzene, deuterated chloroform,deuterated dichloromethane, deuterated DMF, deuterated DMSO, deuteratedethanol, deuterated methanol, and deuterated THF; and any appropriatemixtures thereof.

In another embodiment, the nonaqueous solvent used as the solvent systemin synthesizing the MOF has a pH less than 7. In a further embodiment,the solvent system used to synthesize the MOF is an aqueous solutionthat has a pH less than 7. In yet a further embodiment, the solventsystem used to synthesize the frameworks contains water. In anotherembodiment, the solvent system used to synthesize the frameworkscontains water and hydrochloric acid.

Those skilled in the art will be readily able to determine anappropriate solvent or appropriate mixture of solvents based on thestarting reactants and/or where the choice of a particular solvent(s) isnot believed to be crucial in obtaining the materials of the disclosure.

In a certain embodiment, crystallization of the frameworks can beimproved by adding an additive that promotes nucleation.

In a certain embodiment, the solution, mixture or suspension ismaintained at ambient temperature to allow for crystallization. Inanother embodiment, the solution, mixture, or suspension is heated inisothermal oven for up to 300° C. to allow for crystallization. In yetanother embodiment, activated frameworks can be generated bycalcination. In a further embodiment, calcination of the frameworks canbe achieved by heating the frameworks at 350° C. for at least 1 hour.

In a certain embodiment, the MOF is synthesized in a solvent-free systemthrough mechanical mixing such as ball milling or grinding of thereaction mixture comprised of the linker or moieties, and a metal or ametal/salt complex. The reaction mixture may further contain atemplating agent, growth modulator or other non-linker ligands,catalytic active component or combinations thereof. The reaction mixturemay be heated at an elevated temperature or maintained at ambienttemperature, depending on the reaction components.

After the MOFs are synthesized, the MOFs may be further modified byreacting with one or more post MOF reactants that may or may not havedenticity. In a certain embodiment, the frameworks as-synthesized arenot reacted with a post framework reactant. In another embodiment, theframeworks as-synthesized are reacted with at least one post frameworkreactant. In yet another embodiment, the frameworks as-synthesized arereacted with at least two post framework reactants. In a furtherembodiment, the frameworks as-synthesized are reacted with at least onepost framework reactant that will result in adding denticity to theframework.

It is contemplated by this disclosure that chemical reactions thatmodify, substitute, or eliminate a functional group post-synthesis ofthe MOF with post framework reactant may use one or more similar ordivergent chemical reaction mechanisms depending on the type offunctional group and/or post framework reactant used in the reaction.Examples of chemical reaction mechanisms contemplated by thisarrangement include, but is not limited to, radical-based, unimolecularnucleophilic substitution (SN1), bimolecular nucleophilic substitution(SN2), unimolecular elimination (E1), bimolecular elimination (E2), ElcBelimination, nucleophilic aromatic substitution (SnAr), nucleophilicinternal substitution (SNi), nucleophilic addition, electrophilicaddition, oxidation, reduction, cycloaddition, ring closing metathesis(RCM), pericylic, electrocylic, rearrangement, carbene, carbenoid, crosscoupling, and degradation.

It is yet further contemplated by this disclosure that to enhancechemoselectivity, it may be desirable to protect one or more functionalgroups that can generate unfavorable products upon a chemical reactiondesired for another functional group, and then deprotect this protectedgroup after the desired reaction is completed. Employing such aprotection/deprotection strategy could be used for one or morefunctional groups.

Other agents can be added to increase the rate of the MOF formationreactions disclosed herein, including adding catalysts, bases, andacids.

In another embodiment, the post framework reactant is selected to have aproperty selected from the group comprising, binds a metal ion,increases the hydrophobicity of the framework, decreases thehydrophobicity of the framework, modifies the chemical sorption of theframework, modifies the pore size of the framework, and tethers acatalyst to the framework.

In one embodiment, the post framework reactant can be a saturated orunsaturated heterocycle.

In another embodiment, the post framework reactant has 1-100 atoms withfunctional groups including atoms such as N, S, O, P and transitionmetals.

In yet another embodiment, the post framework reactant is selected tomodulate the size of the pores in the framework.

In another embodiment, the post framework reactant is selected toincrease the hydrophobicity of the framework. In an alternativeembodiment, the post framework reactant is selected to decrease thehydrophobicity of the framework.

In yet another embodiment, the post framework reactant is selected tomodulate chemical, inorganic and/or organic sorption of the framework.

In yet another embodiment, the post framework reactant is selected tomodulate gas separation of the framework. In a certain embodiment, thepost framework reactant creates an electric dipole moment on the surfaceof the framework when it chelates a metal ion.

In a further embodiment, the post framework reactant is selected tomodulate the gas sorption properties of the framework. In anotherembodiment, the post framework reactant is selected to promote orincrease hydrocarbon gas sorption of the framework.

In yet a further embodiment, the post framework reactant is selected toincrease or add catalytic efficiency to the framework.

In another embodiment, a post framework reactant is selected so thatorganometallic complexes can be tethered to the framework. Such tetheredorganometallic complexes can be used, for example, as heterogeneouscatalysts.

To improve MOF catalyst usage the following are possible ways to improvethe MOF and or determine the best possible MOF support to utilize. Theorganic linkers and nodes could be selected to achieve MOFs with largepore size and improve the diffusion of reactants and reagents throughthe MOF catalyst, improving catalyst life. Growth modulators could beused to create defects in the MOF structure to also improve diffusionand catalyst life. Synthetic modification of the organic linker could bedone to increase the hydrophobicity of the MOF. This increases the localconcentration of desired reactant molecules around the acid sites andoptimize catalyst selectivity. Aside from the MOF nodes and linkers,non-linker ligands could be used as attachment points for acid sites,which expands the types of MOF supports that could be used to make theacid MOF catalysts. It is envisioned that by using some or all of theparameters above one can be able to select MOFs for improved alkylationand/or oligomerization catalytic activity.

Examples of MOFs

The following additional examples of certain embodiments of theinvention are given. Each example is provided by way of explanation ofthe invention, one of many embodiments of the invention, and thefollowing examples should not be read to limit, or define, the scope ofthe invention.

Table 1 below lists some exemplary MOFs that are currently used

TABLE 1 Chanel Pore Name Nodecomp. Topology Type Size (Å) HKUST-1 Cu tbo3D 12 MIL-101 Al, Fe, Cr mtm 3D 16, 29, 34 UiO-66 Zr, Hf, Ce fcu 3D 8UiO-67 Zr, Hf fcu 3D 12 MOF-808 Zr, Hf, Ce spn 3D 16 PCN-777 Zr, Hf spn3D 32 PCN-224 Zr, Hf she 1D 20 PCN-222 Zr, Hf csq 1D 37 NU-1000 Zr, Hfcsq 1D 31

The linkers currently used to build MOFs are shown in FIG. 1.

Non-limiting examples of ways to create acid sites in MOFs include thefunctionalization of metal nodes with oxyanions, encapsulatingheteropolyacids on the MOFs, grafting sulfonic acids on the MOFs, oreven immobilization of ionic liquids on MOFs. It is expected thatindividual physical tests can be run to determine the best MOFs forcatalytic applications.

These acid MOFs can then be tested differently using methods such as:Oligomerization testing (for oligomerization activity and long termstability), Alkylation testing (for cracking activity, oligomerizationactivity, alkylation performance and stability), and Batch ReactorTesting (Testing for activity for isomerization, activity for alkylationand activity hydride transfer).

Example 1 Ionic Liquids in MOFs

For MOF-supported Ionic Liquids (ILs), the anchor point could be themetal node or a functional group on the linker. ILs are salts with a lowmelting point, typically less than 100° C. The origin of the low meltingpoint is the charge delocalization in its bulky constituent ions,leading to small lattice enthalpies and large entropy changes that favormelting. The variety of choices for cations and anions provides a highsynthetic flexibility for ILs, and this flexibility is magnified by theability to make IL mixtures.

ILs can display Lewis or Brønsted acidity or both. Most of the knownLewis acidity comes from the electron-pair-accepting ability of theanion, while Brønsted acidity can come from the cation and/or the anion.Additional Brønsted sites such as —SO₃H can also be introduced throughalkyl side chains tethered to the ionic core.

For alkylation, ILs containing multinuclear halometallate anions such as[Al₂Cl₇]⁻ are highly active and are thus among the synthetic targets forMOF-based alkylation catalyst in this invention.

Example 2 MOF-Supported Heteropolyacids

Heteropolyacids (HPAs), specifically phosphotungstic acid (PTA), hadbeen encapsulated in MOF pores. MOFs used to host H₃PW₁₂O₄₀ includeMIL-100, MIL-101, UiO-67, NU-1000, HKUST-1, ZIF-67 and ZIF-8. HPAs aresolid acids that incorporate transition metal-oxygen clusters as anions.They are called the Keggin and Wells-Dawson structures, and like otherHPA anions, they feature metal-oxygen octahedra as a basic structuralunit. The most common metals that make up the octahedra are tungsten,molybdenum, and vanadium. The anion is formed when these octahedrasurround one or more heteroatoms, which are often phosphorous orsilicon. The acidity of HPAs is purely Brønsted in nature. For thecommercially available Keggin-type HPAs, the acid strength decreases inthe order H3PW12O40>H4SiW12O40>H3PMol2O40>H4SiMol2O40. H3PW12O40 (calledphosphotungstic acid, hereon referred to as PTA) was found to be moreacidic than H2SO4 and is therefore a suitable acid site candidate tomake acid MOF catalysts.

With MIL-101, the PTA loading could be as high as 60% by weight. Thesynthesis is also facile. PTA can be added to the MOF synthesis mixturein a one-pot type ship-around-bottle synthesis or it can be impregnatedinto the MOF post-synthesis. A common concern with supported PTA is thestrong interaction between PTA and traditional supports like silica,which lowers the acidity of the former. The nature of the MOF buildingblocks gives it different surface properties, which can be tuned tominimize any effects on the acidity of encapsulated PTA

In one embodiment, a metal organic framework composition can comprise asolid metal organic framework supported heteropolyacid wherein theheteropolyacid loading is greater than 25% by weight and the pore volumeis less than 2 mL/g. In one non-limiting embodiment, the composition canbe formed by forming a solution containing a heteropolyacid and asolvent to form a heteropolyacid solution, soaking a metal organicframework in the heteropolyacid solution to form an impregnated metalorganic framework, and drying the impregnated metal organic framework toform a solid metal organic framework supported heteropolyacid. Inanother non-limiting embodiment, the composition can be formed by mixinga solution of solid metal organic framework starting reagents and aheteropolyacid to form a starting solution and reacting the startingsolution in a reactor to form a solid metal organic framework supportedheteropolyacid.

In one non-limiting embodiment, the pore volume of the solid metalorganic framework supported heteropolyacid is less than 2 mL/g. Inanother non-limiting embodiment, the BET surface area of the solid metalorganic framework supported heteropolyacid is less than 4,500 m²/g.

Non-limiting examples of HPAs include H₃PW₁₂O₄₀, H₃PMo₁₂O₄₀, H₃SiW₁₂O₄₀,H₆P₂Mo₁₈O₆₂.

The process of a reaction can be a heterogenous reaction between a solidmetal organic framework supported heteropolyacid catalyst and ahydrocarbon feed. This modified hydrocarbon stream can compriseessentially of C₆₊ hydrocarbons.

Preparation of HPA Materials:

PTA. The reference PTA catalyst was prepared heat-treatingphosphotungstic acid hydrate at 300° C. to dehydrate the sample prior tocatalyst testing.

Silica-supported PTA catalyst (PTA@SiO₂). This reference catalyst wasprepared via solution impregnation. Silica gel was immersed in asolution of PTA in H₂O. The solid was separated by filtration and driedin a vacuum oven.

MIL-101. The MIL-101 MOF used as support for PTA was synthesized bydissolving Cr(N₀₃)_(3·)9H₂O in an aqueous solution of HNO₃. Terephthalicacid was then added. The MOF synthesis was then carried out in a Parrreactor at a suitable temperature for MOF formation. The product,MIL-101, was washed with H₂O and ethanol prior to air-drying.

MIL-101-supported PTA prepared via solution impregnation. Two sampleswere prepared as follows: (1) A solution of PTA in H₂O was firstprepared. MIL-101 was immersed in this solution. The solid was separatedby centrifugation, air-dried and then dried in an oven. This sample isdenoted as imp-PTA@MIL-101. (2) The second sample was prepared using thesame procedure as (1), except the pH of the PTA solution was adjusted byusing an aqueous solution of HNO₃. This sample is denoted asimp-PTA@MIL-101-pH.

MIL-101-supported PTA prepared via one-pot synthesis. Two samples withdifferent PTA loadings were prepared. The same synthesis as MIL-101 wasfollowed except PTA was dissolved in the reaction mixture prior toloading into the Parr reactor. Different PTA loadings were achieved byvarying the amount of PTA added to the MIL-101 reaction mixture. Thesamples are denoted as op-PTA@MIL-101 and op-PTA@MIL-101-low, for thenormal and lower loading samples, respectively.

Characterization of HPA Materials

The PTA loading and textural properties of the supported PTA sampleswere determined by XRF and N₂ physisorption analyses, respectively.Please see Table 2

TABLE 2 Weight % BET Pore PTA Surface Volume Material Type Material fromXRF Area (m2/g) (mL/g) Support silica gel — 474 0.91 MIL-101 — 3030 1.34Silica gel-supported PTA PTA@SiO₂ 30 389 0.74 via wet impregnation 62711 0.34 MIL-101-supported PTA imp-PTA@MIL-101 63 821 0.38 via wetimpregnation imp-PTA@MIL-101-pH MIL-101-supported PTA op-PTA@MIL-101 65720 0.35 via one-pot synthesis op-PTA@MIL-101-low 34 1963 0.93

The PTA loading for the reference PTA@SiO₂ sample was 30%, which isenough to disperse a monolayer of PTA on the surface of the silicasupport. High PTA loadings in MIL-101 (34 to 65% by weight) wereachieved.

Different analysis such as XRD and IR spectroscopy were carried out. TheXRD patterns of the MIL-101 supported PTA samples compared to pure PTAand MIL-101 are shown in FIG. 2. The IR spectroscopy of the samples areshown in FIG. 3.

Catalytic Tests for HPA Materials—Alkylation

PTA and the supported PTA samples were evaluated for both liquid-phaseand supercritical-phase alkylation of isobutane and trans-2-butene. Allreactions were carried out in a fixed-bed reactor. Reactor effluentswere analyzed by an on-line GC using an FID detector. The samples werescreened by loading the catalyst into the reactor and testing at thesame activation and run temperatures, and isobutane-to-olefin of thefeed. All samples were activated in situ at pre-selected temperaturesunder a flow of N₂. Bare PTA samples were also dehydrated in a furnaceto remove most of the water of hydration prior to loading into thereactor. Fresh catalyst was used for each run.

Results from the isobutane/trans-2-butene alkylation tests using PTA andPTA@SiO₂ catalysts are shown in FIG. 4 and FIGS. 5a and 5 b.

FIG. 4 depicts alkylation results of showing trans-2-butene conversionand C₈ paraffin selectivity versus catalyst age for PTA. Test conditionsfor FIG. 4 were: activation temperature=225° C., reactiontemperature=room temperature, isobutane-to-olefin ratio=15, WHSV=0.12h−1.

FIG. 5a depicts conversion v. catalyst age alkylation results and FIG.5b depicts C₈ selectivity v. conversion % under different testconditions for PTA@SiO₂. The legend indicates the activation temperature(act), reaction temperature (r×n), isobutane-to-olefin ratio (I/O) andweight hourly space velocity (WHSV) for each test.

FIG. 6a depicts conversion v. catalyst age alkylation results and FIG.6b depicts C₈ selectivity v. conversion % for op-PTA@MIL-101 sampleswith results for PTA@SiO₂ tested under similar WHSV are included forcomparison. Test conditions for FIG. 6a and FIG. 6b were: activationtemperature=225° C., reaction temperature=room temperature, reactionpressure=300 psi and isobutane-to-olefin I/O=15.

FIG. 7a depicts conversion v. catalyst age alkylation results and FIG.7b depicts C₈ selectivity v. conversion % depicts alkylation results forimp-PTA@MIL-101 samples with results for PTA@SiO₂ tested under similarWHSV are included for comparison. Test conditions for FIG. 7a and FIG.7b were: activation temperature=225° C., reaction temperature=roomtemperature, reaction pressure=300 psi and isobutane-to-olefin I/O=15.

FIG. 8a and FIG. 8b depicts the supercritical alkylation using PTA@SiO₂and imp-PTA@MIL-101-pH as catalyst. Test conditions for FIG. 8a and FIG.8b were: activation temperature=225° C., reaction temperature=137° C.,reaction pressure=653 psig and isobutane-to-olefin I/O=33.25.

FIG. 9 depicts the activity in a batch reactor for imp-PTA@MIL-101 forthe oligomerization of isobutene, trans-2-butene and propylene in termsof conversion versus time.

FIG. 10 depicts the product selectivity of imp-PTA@MIL-101 for theoligomerization of isobutene, trans-2-butene and propylene in a batchreactor.

Example 3 Sulfonic Acid-Functionalized MOFs

Catalysts bearing perfluorinated sulfonic acid groups have high acidstrength. A well-known example is Nafion, which had been reported inliterature as an alkylation catalyst. In this invention, solid acidcatalysts comprised of MOFs bearing halogenated and non-halogenatedalkyl- and arylsulfonic acid sites are targeted.

The solid acid catalysts disclosed in this example are MOFsfunctionalized with halogenated and non-halogenated alkyl and arylsulfonic acids. The functionalized MOF is prepared by a reaction betweenthe nucleophilic groups present in the MOF's building units and cyclicsulfonate esters called sultones. Such reaction can yield sulfonic acidsin the MOF's internal surface. These MOFs may be used as acid catalysts,even for those reactions that require high acid strength such asisoparaffin-olefin alkylations. Using perflourinated sultones can yieldperfluorosulfonic acid sites on the MOFs, reminiscent of the highlyacidic sites found in Nafion, and thus yielding an acid MOF catalystthat is a suitable candidate for alkylation catalysis.

FIG. 11 shows the reaction scheme for the condensation between a MOFhydroxyl and a sultone. FIG. 12 shows examples of MOF building unitsbearing such nucleophilic functionalities such as amino- and hydroxylgroups. FIG. 13 shows examples of MOF ligands bearing such nucleophilefunctionalities such as amino and hydroxyl groups.

Sultones that can be used for this synthesis include, but are notlimited to, the examples shown in FIG. 14.

In one embodiment, the solid metal-organic framework composition cancomprise a solid metal-organic framework supported sulfonic acid whereinthe sulfur content is greater than 0.5 mmol/gram. The composition ofsolid metal organic framework supported sulfonic acid can be made byreacting the metal organic framework with sultones in solution attemperatures ranging from 25° C. to 200° C. to form the sulfonicacid-functionalized metal organic framework. The functionalized metalorganic framework is dried to obtain the solid metal organic frameworksupported sulfonic acid. In one embodiment the reaction of the metalorganic framework with the sultone occurs without any external appliedheat.

Alternatively, perfluorinated sulfonic acid sites can be generated inMOFs using multifunctional organic molecules, where one functionality isthe perfluorinated sulfonic acid group and the other is a binding motiffor the metal organic framework such as, but not limited to, acarboxylate or another sulfonic acid group.

The process of a reaction can be a heterogenous reaction between a solidmetal organic framework supported sulfonic acid and a hydrocarbon feed.This modified hydrocarbon stream can comprise essentially of C₆₊hydrocarbons.

Preparation of Sulfonic Acid-Functionalized MOFs

MOF-808. MOF-808 was synthesized by dissolving ZrOCl₂·8H₂O in formicacid. 1,3,5-benzenetricarboxylic acid was also dissolved in anhydrousDMF to create a separate solution. The two solutions were mixed, allowedto react under suitable conditions to form the MOF, and the solids wereextracted. The solids were then treated with HCl. Finally, the solidswere washed, air-dried and then heat-treated.

Hf-MOF-808. Hf-MOF-808 was prepared in the same manner as MOF-808,except using HfCl₄ instead of ZrOCl₂·8H₂O as metal precursor for thesynthesis.

MIL-101. MIL-101 was synthesized by dissolving Cr(NO₃)₃·9H₂O in anaqueous solution of HNO₃. Terephthalic acid was then added and reactedin a heated reactor. The product was then extracted and heat treated.

Sulfonic Acid Functionalization of MOF Supports. Sulfonic acid siteswere incorporated in MOFs by refluxing the MOFs in a toluene solution ofthe desired sultone under inert atmosphere. After the reaction mixtureis cooled down to room temperature, the solids were washed and dried toobtain the solid sulfonic acid-functionalized MOFs.

Properties:

Both MOF and silica supports were functionalized with sulfonic acids todemonstrate the different sulfur content in the sultone grafted product.Table 3 depicts the results

TABLE 3 Sulfonic acid to MOF Node S content in Ratio in MOF graftedproduct Support Sultone Sample Name Product (mmol/g) MOF-808 1,4-butanesultone C₄H₈SO₃H@MOF-808 3.6 2.09 MIL-101 C₄H₈SO₃H@MIL-101 1.1 1.47MOF-808 hexafluoro(3- C₃F₆SO₃H@MOF-808 2.3 1.85 Hf-MOF-808 methyl-1,2-C₃F₆SO₃H@Hf-MOF-808 1.7 0.83 Commercial oxathietane)-2,2-C₃F₆SO₃H@SBA-15 N/A 0.17 Silica dioxide Sample A CommercialC₃F₆SO₃H@MCM-41 N/A 0.28 Silica Sample B MOF-808 1-(nonafluorobutyl)C₆F₁₂SO₃H@MOF-808 1.2 1.07 trifluoroethane sultone

Catalytic Tests for Sulfonic Acid-Functionalized MOFs—Alkylation

Samples were evaluated for both liquid-phase and supercritical-phasealkylation of isobutane and trans-2-butene. All reactions were carriedout in a fixed-bed reactor. Reactor effluents were analyzed by anon-line GC using an FID detector. The samples were screened by loadingthe catalyst into the reactor and testing at the same activation and runtemperatures, and isobutane-to-olefin of the feed. All samples wereactivated in situ at pre-selected temperatures under a flow of N₂. Freshcatalyst was used for each run.

Two methods were used to for the regeneration of the partiallydeactivated catalyst bed. One is by heating under N₂. The second methodwas supercritical isobutane regeneration at temperatures and pressuresabove the supercritical point for isobutane.

FIG. 15, FIG. 16, and FIG. 17 depict the liquid-phase alkylation ofisobutane with trans-2-butene using different sulfonic acid-decoratedMOF catalysts.

FIG. 15 depicts alkylation results for C₃F₆SO₃H@MOF-808 catalystsamples. Test conditions for FIG. 15 were: reaction temperature=80° C.,reaction pressure=300 psi and isobutane-to-trans-2-butene ratio I/O=134,and weight hourly space velocity of 0.12 h⁻¹. The sulfonic acid to MOFnode ratio in the product was 1.5 with a S content in the sultone gratedproduct of 1.97 mmol/g.

FIG. 16 depicts alkylation results for C₆F₁₂SO₃H@MOF-808 catalystsamples. Test conditions for FIG. 16 were: reaction temperature=80° C.,reaction pressure=300 psi and isobutane-to-trans-2-butene ratio I/O=134,and weight hourly space velocity of 0.12 h⁻¹. The sultone to MOF noderatio in the product was 1.2 with a S content in the sultone gratedproduct of 1.07 mmol/g.

FIG. 17 depicts alkylation results for C₃F₆SO₃H@Hf-MOF-808 catalystsamples. Test conditions for FIG. 17 were: reaction temperature=80° C.,reaction pressure=300 psi and isobutane-to-trans-2-butene ratio I/O=128,and weight hourly space velocity of 0.10 h⁻¹. The sulfonic acid to MOFnode ratio in the product was 1.7 with a S content in the sultone gratedproduct of 0.83 mmol/g.

FIG. 18 depicts the supercritical alkylation of isobutane andtrans-2-butene with a sulfonic acid-decorated MOF (C₃F₆SO₃H@MOF-808).Test conditions for FIG. 18 were: reaction temperature=137° C., reactionpressure=635 psi and isobutane-to-trans-2-butene ratio I/O=134, andweight hourly space velocity of 0.07 h⁻¹. The sultone to MOF node ratioin the product was 2.34 with a S content in the sultone grated productof 1.85 mmol/g.

FIG. 19 depicts the alkylation results for C₃F₆SO₃H@MOF-808 catalystsamples. Test results for FIG. 19 were: reaction temperature=80° C.,reaction pressure=300 psi and isobutane-to-olefin ratio I/O=76, andweight hourly space velocity of 0.13 h⁻¹.

FIG. 20 depicts alkylation results for C₃F₆SO₃H@MOF-808 catalyst withsupercritical isobutane regeneration. In supercritical isobutaneregeneration the feed is switched from the reaction mixture to pureisobutane to stop the alkylation step. After flushing with isobutane for30 min, the reactor temperature was increased to 137° C. and thepressure to 653 psi. Supercritical isobutane regeneration was carriedout for 4 h at a WHSV of 33 h⁻¹. After the regeneration step wascompleted, the reactor is brought back to the reaction temperature andpressure, and the flow of the reaction mixture was started for the nextalkylation step. Test results for FIG. 20 were: reaction temperature=80°C., reaction pressure=300 psi and isobutane-to-olefin ratio I/O=134, andweight hourly space velocity of 33 h⁻¹.

FIG. 21 depicts alkylation results for C₃F₆SO₃H@MOF-808 catalyst withregeneration under N₂ flow. In regeneration under N₂ flow after stoppingthe reaction mixture flow, the reactor is flushed for 30 min with a 50mL/min flow of N₂. The reactor temperature was then increased to 110° C.and the pressure dropped to atmospheric. After 12 h of regeneration, thereactor is brought back to the reaction temperature and pressure, filledthroughout with isobutane and the flow of the reaction mixture wasstarted for the next alkylation step. FIG. 21 were: reactiontemperature=80° C., reaction pressure=300 psi and isobutane-to-olefinratio I/O=134, and weight hourly space velocity of 0.15 h⁻¹.

The product distribution from the alkylation of isobutane withtrans-2-butene catalyzed by a perfluorinated sulfonicacid-functionalized MOF (C₃F₆SO₃H@MOF-808) is shown in Table 4. Reactionconditions: temperature=80° C., pressure=300 psi, and weight hourlyspace velocity (WHSV)=0.13 h⁻¹. The production of C₈ paraffins indicatesthat this acid MOF is capable of catalyzing the alkylation reaction ofisobutane with trans-2-butene. TMP is trimethylpentane, and DMH isdimethylhexane.

TABLE 4 TOS (min) 35 Olefin Conversion (%) 87 C₅₊ product distribution(%) C₅-C₇ 14 C₈ 41 C₈₌ 20 C₉₊ 25 C₈ product distribution (%) 2, 2, 4-TMP11 2, 2, 3-TMP 1 2, 3, 4-TMP 20 2, 3, 3-TMP 12 DMHs 56

Catalytic Tests for Sulfonic Acid-Functionalized MOFs—Oligomerization

Oligomerization catalytic testing was performed in a pressurized batchreactor. The catalyst was pre-treated using vacuum and heat. Then thereactor was pressurized with the desired olefin. The pressure andtemperature were monitored and was used to calculate conversion. At theend of the run a gas sample was collected and analyzed by gaschromatography to determine the product distribution.

We describe of using sulfonic acid functionalized-MOF-808 to oligomerizeisobutane (iC₄), propylene (C₃), and trans-2-butylene(t2b). The activityis compared to MOF-808 SO₄.

FIG. 22 depicts the results of the oligomerization reaction over thevarious sulfonic acid-functionalized MOF-808 materials over time.MOF-808-SO₄, described in the next Example, was included in the plot asa reference.

FIG. 23 depicts the product selectivity for the oligomerization reactionover the various sulfonic acid-functionalized MOF-808 materials overtime. MOF-808-SO₄, described in the next Example, was included in theplot as a reference.

Example 4 Oxyanion-Modified Metal Organic Frameworks

In one example a superacidic MOF can be sulfated into MOF-808. This MOFanalogue of sulfated zirconia (SZ) is prepared by immersing MOF-808 indilute H₂SO₄, resulting in adsorbed sulfates on the MOF's zirconiumoxocluster node. The sulfated node (˜0.5 nm in size) can be considered anano-sized SZ.

In this example we describe a process that uses an acidic MOF that canselectively oligomerize light olefins (C₃-C₆) to more valuable, heavierproducts (high octane gasoline, low sulfur diesel, jet fuel, specialtysolvents or synthetic lube oils) which have been forecast to have greatgrowth potential despite the forecasted changes in gasoline demand. Asan example of how this process might be applied a MOF capable ofreacting only with isobutene can be used to upgrade a mixed C₄ olefinfeed into to a more valuable C₁₂ and C₈ olefin stream.

MOFs can also be made with different metals as nodes and different acidsite functionalities. As described above the metal ion nodes could becomposed of one or more metal ions from Group 1 through 16 of the IUPACPeriodic Table of the Elements including actinides, and lanthanides, andcombinations thereof.

The loading of the metals on the nodes can be 1 atom per node, 2 atomsper node, 3 atoms per node, 4 atoms per node, 5 atoms per node, 6 atomsper node, 7 atoms per node, or even 8 atoms per node or more. In onenon-limiting example oxygen can be loaded onto the solid metal organicframework from 1 atom per node, 10 atoms per node, 20 atoms per node, oreven 25 atoms per node and greater.

The composition of an oxyanion-modified metal organic framework can bemade by mixing a previously prepared solid metal-organic framework and asolution of suitable concentration of the desired oxyanion in eitheraqueous or organic media. The resulting suspension is allowed to reactand equilibrate over a suitable period of time. The solid can then bethen recovered, washed and dried to form an oxyanion-modified metalorganic framework.

The process of a reaction can be a heterogenous reaction between a solidoxyanion-modified metal organic framework and a hydrocarbon feed. Thismodified hydrocarbon stream can comprise essentially of C₆₊hydrocarbons.

Oxyanion-modified Metal Organic Frameworks examples:

Zr-MOF-808 Base material. A solution of zirconium oxychloride and formicacid in DMF was combined with a solution of BTC linker in DMF. Thesolution was placed in an oven and heated to a suitable temperature forthe formation of the MOF structure. The MOF precipitate was collected bycentrifugation and washed with of fresh solvent and heat treated toyield activated sample.

Hf-MOF-808 Base material. A solution of hafnium oxychloride and formicacid in DMF was combined with a solution of BTC linker in DMF. Thesolution was placed in an oven and heated to a suitable temperature forthe formation of the MOF structure. The MOF precipitate was collected bycentrifugation and washed with of fresh solvent and heat treated toyield activated sample.

Ce-MOF-808 Base material. A solution of cerium ammonium nitrate andformic acid in DMF was combined with a solution of BTC linker in DMF.The solution was placed in an oven and heated to a suitable temperaturefor the formation of the MOF structure. The MOF precipitate wascollected by centrifugation and washed with of fresh solvent and heattreated to yield activated sample.

Example of an oxyanion-modified metal-organic framework: Zr-MOF-808-SO₄.Zr-MOF-808 was immersed in a solution of sulfuric acid. The mixture wasallowed to react for a suitable amount of time and the solids werecollected. The modified MOF can be washed and heat treated to yield theactivated sample.

Properties:

Table 5 below depicts the energy dispersive X-ray spectroscopy data ofelement distribution and relative composition of a samples surface.

TABLE 5 Zr-MOF-808-SO4 Element C O S Zr Hf Atomic % 55.7 35.7 1.7 6.70.1 Atoms/node 49.8 32.0 1.5 6.0 0.1 Zr-MOF-808-PO4 Element C O P Zr HfAtomic % 59.2 32.4 0.3 6.8 0.1 Atoms/node 52.5 28.8 0.3 6.0 0.1Hf-MOF-808-SO4 Element C O S Hf Atomic % 51.8 37.2 2.8 8.2 Atoms/node38.0 27.3 2.1 6.0 Hf-MOF-808-PO4 Element C O P Hf Atomic % 52.9 38.1 0.18.9 Atoms/node 35.7 25.7 0.0 6.0 Ce-MOF-808-SO4 Element C O S Ce Atomic% 55.8 35.5 0.6 8.1 Atoms/node 41.3 26.3 0.4 6.0 Ce-MOF-808-PO4 ElementC O P Ce Atomic % 56.6 35.3 0.0 8.1 Atoms/node 41.8 26.1 0.0 6.0

Catalytic Tests for Oxyanion-modified Metal-OrganicFrameworks-Oligomerization

Catalytic testing procedure: a plug-flow reactor was loaded withoxyanion-modified metal-organic framework mixed with a diluent. Prior totesting the catalyst was heat treated overnight under a flow ofnitrogen. The reactor was pressurized using an inert reagent such asisobutane prior to flowing the feed. The temperature was controlledusing a clam furnace. Flow of premixed isobutene/isobutane feed wasachieved via a pump at a suitable rate for the appropriate time. SeeFIG. 24 for an example of conversion as a function of time on stream.

Additional testing of the Zr-MOF-808-SO₄ catalyst in the plug-flowreactor for over 300 hours is shown in FIG. 25 wherein the MOF materialis capable of achieving high conversion without deactivation for longperiods of time. It is theorized that, the MOF architecture allows forC₈ and C₁₂ product to evacuate the channels and pores of the catalystwithout being permanently trapped due to the high surface area and largepore size of the material.

As shown in FIG. 26, this process utilizes a fixed-bed reactor whichcontains a bed of MOF material to convert a stream of mixed isobuteneinto liquid products that are separated from the unconverted or lightmaterial. The liquid product contains a mixture of only C₈ olefins andC₁₂ olefins which can be separated further into two individual streamsor be used as a mixture.

Table 6 below lists the conditions used in this experiment and showsthat the reaction can proceed under mild conditions. The presence ofpressurized isobutane is designed to enable higher molecular weightmolecules to be removed from the surface of the catalyst to preventcatalyst deactivation by active site fouling. It is anticipated that theselectivity of the product towards C₈s or C₁₂s can be controlled bycontrol of the space velocity (WHSV) and the concentration of olefin inthe feed. We expect that higher concentration of olefin and lower spacevelocities will favor C₁₂s because the increased residence time in thecatalyst will allow for more olefins to be in close contact leading tohigher rate of oligomerization reactions to occur. In contrast, athigher WHSV values and more diluted C4 olefin feed, C8s will tend to befavored due to the lower number of olefin-olefin encounters.

TABLE 6 Testing conditions used to generate data. Parameters Value FeedIsobutane and Isobutene Olefin content 6.7% Temperature 80° C. Pressure300 psi WHSV (olefin) 0.4

Analysis of the product effluent and the collection times are listed inTable 7. The high selectivity toward C₈ and C₁₂ olefins is theorized tobe from a combination of factors such as large pore size and narrowacidity range of the catalyst active sites.

TABLE 7 Composition of the effluent stream demonstrating the highselectivity for C₈ olefins and C₁₂ olefins product and low heavyimpurity. Sample 1 Sample 2 Sample 3 Time on Stream (h) 143      167       191       Conversion 89%   92%   92%   Product Selectivity (wt%) C₈ olefins 41.1% 40.0% 38.9% C₁₂ olefins 58.5% 59.7% 60.7% C₁₆₊olefins  0.4%  0.2%  0.4%

In this example different MOF's with different pore sizes were used forlight olefin oligomerization. MOF-808 with a pore size of 14 Å, PCN-777with a pore size of 32 Å, and NU-1000 with a pore size of 32 Å weretested.

FIG. 27 depicts oligomerization completion rates in these varioussulfated MOFs.

Table 8 below describes the pore variation effect on oligomerizationactivity in oxyanion MOFs

TABLE 8 Molecule (mol %) MOF-808-SO₄ PCN-777-SO₄ C₈ Olefin 94.2 92.3 C₁₂Olefin 4.7 7.5 C₁₂₊ Olefin 0.1 0.2

In closing, it should be noted that the discussion of any reference isnot an admission that it is prior art to the present invention,especially any reference that may have a publication date after thepriority date of this application. At the same time, each and everyclaim below is hereby incorporated into this detailed description orspecification as an additional embodiment of the present invention.

Although the systems and processes described herein have been describedin detail, it should be understood that various changes, substitutions,and alterations can be made without departing from the spirit and scopeof the invention as defined by the following claims. Those skilled inthe art may be able to study the preferred embodiments and identifyother ways to practice the invention that are not exactly as describedherein. It is the intent of the inventors that variations andequivalents of the invention are within the scope of the claims whilethe description, abstract and drawings are not to be used to limit thescope of the invention. The invention is specifically intended to be asbroad as the claims below and their equivalents.

1) A solid metal organic framework composition comprising: a solidoxyanion-modified metal organic framework wherein the oxyanion loadingis at least 2 per node. 2) The composition of claim 1, wherein theoxyanion is selected from the group consisting of: FSO₃ ⁻, ClSO₃ ⁻CF₃SO₃ ⁻, PO₄ ³⁻, ClO⁻, ClO₄ ⁻, ReO₄ ²⁻, SO₄ ²⁻ and combinationsthereof. 3) The composition of claim 1, prepared by a method comprising:mixing a solution of a solid metal organic framework and an oxyanion;drying the oxyanion-modified metal organic framework. 4) The compositionof claim 1, wherein the solid oxyanion-modified metal organic frameworkis used in a heterogeneous hydrocarbon conversion reaction. 5) Thecomposition of claim 1, wherein the solid oxyanion-modified metalorganic framework converts C₂ to C₅ hydrocarbons into C₆₊ hydrocarbons.